Re: Possible bug in zfs send or pipe implementation?

Am 2024-07-14 05:19, schrieb Garrett Wollman:
> <<On Sat, 13 Jul 2024 19:42:32 -0700, Rick Macklem 
> <rick.macklem@gmail.com> said:
> 
>> # ps axHl
>> should show you what wchan's the processes are waiting on and that 
>> might
>> give you a clue w.r.t. what is happening?
> 
> zfs is waiting to write into the pipe and pv (the progress meter) is
> waiting in select.
> 
>> If is easy to build a kernel from sources and boot that, you could try 
>> defining
>> PIPE_NODIRECT in sys/kern/sys_pipe.c and see if that avoids the hangs?
> 
> It's easy to build a kernel from sources, but not easy to reboot the
> server -- it's being retired shortly, and because of time constraints
> I need to get it drained before the next scheduled outage.

As you need to stop the process anyway: I always use mbuffer with "-m 
50M" (50M buffer, and with "-v 2" you will also get some progress info) 
between the sender and the receiver. This may or may not change the 
behavior your see (given you have some time constraint which prevents 
certain investigative stuff and gives priority to get the job done).

Bye,
Alexander.

-- 
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